This invention relates to machines used for preparing popcorn and more specifically, to a popcorn machine which uses a solid state controller to control the popping operation.
Referring to FIG. 1, popcorn popping machines for concession stand, restaurant, or home use are well known. Generally, conventional such popping machines have a cabinet in which the popcorn is both popped and stored. Unpopped popcorn kernels are typically loaded into a kettle P38. The popcorn kernels are combined with salt and cooking oil, and heated. The kettle in a conventional such machine has electrical heating elements P40 as part of the bottom wall of the kettle. The heating elements heat the oil and the popcorn kernels and thereby effect popping of the kernels. As the volume of the popping popcorn expands in the kettle, an initial portion of the popped popcorn lifts the cover P44, overflows out the top of the kettle, and discharges into the popcorn cabinet. The remainder of the popped popcorn is subsequently dumped from the kettle. An exhaust blower is typically used to vent the interior of the cabinet.
In some known popcorn machines, the various parts of the machine such as oil injection, kettle heating and exhaust systems are activated manually. In such case, a user must correctly add popcorn and oil, activate the kettle heat, and turn off the kettle heat when a popping cycle has been completed. Kettle temperature is typically controlled at about 400 degrees F. Further, with manual operations, the user is subject to injury from any direct contact with hot oil, hot kettle, or hot heating elements.
Popcorn poppers currently in use share common designs, generally as follows:
A heater P40 is affixed to, or is a part of, the bottom of kettle P38, whereby the kettle and the heater are an integral, one-piece, unit, whereby any movement of the kettle is, by definition, a corresponding movement of the heater.
The heat required is generally supplied by a 220 volt AC power supply delivering approximately 5.5 kW of power to nickel-chromium heaters.
The kettle is hinged or otherwise pivotably mounted about a pivot structure, which is part of base P44, to enable dumping of popped popcorn contents from the kettle when activated manually by a worker/operator.
Because of the dump requirement, the heater in the bottom of the kettle necessarily moves with the kettle as the kettle dumps. The kettle heater is connected to the electrical power source using cable P41 and connector P42. Cable breakage from metal fatigue is limited by using heavy duty cables; although the cables cannot be so heavy as to interfere with cable movement/flexing while the kettle is being dumped.
Kettle cover P44 rises when the popped corn pushes the cover up, indicating the near termination of the popping cycle.
At the end of the popping cycle, the operator/worker turns OFF power to the heater, and dumps the popped popcorn from the kettle into the bottom of the cabinet.
The sequence of operation for some conventional popcorn poppers is as follows:
A worker turns the unit and the heaters ON, and waits for the unit to heat to operating/popping temperature.
The worker turns ON the stirring mechanism and the oil supply, thus introducing cooking oil into the kettle.
The worker raises the cover and dumps popcorn kernels and salt into the kettle, being careful to avoid splashing the hot oil from the kettle.
The worker waits for popping to begin. When the popping popcorn lifts the cover, or when the popping has almost stopped, the worker manually turns OFF the heat, grasps the dump handle, and dumps the popped popcorn out of the kettle.
The worker turns the heat back ON when he/she desires to start the next cycle of popping more popcorn.
The above process thus requires frequent intervention by a worker to prevent popcorn from burning if the heat is not turned off or the kettle is not dumped at the proper time. Or, if the heat is turned off too soon, some kernels which would otherwise pop will not have popped, leaving an excess number of unpopped kernels in the kettle.
In a more recent development, a microprocessor is integrated into the control panel of a popcorn popper in order to at least partially automate the popping cycle. Such microprocessor controls timing and power levels to preheat the oil, to pump the oil into the kettle, to turn on and off the power to the kettle, to turn on and off the exhaust fan, to turn on and off the agitator/paddle, to control intensity of heat to the kettle, and to control an alarm system sensitive to overheating of the kettle. In such system, the popping cycle is controlled by the microprocessor, using a timer which turns off kettle heating power to the nickel chromium heating elements at a predetermined time, e.g. ten minutes, after the start of the popping cycle/process.
Such popcorn popping machines have no capability to automatically dump the popped popcorn, or to start a new popping cycle without operator/worker intervention.
Nor do such popcorn popping machines have any capability to sense the actual progression of the popping process in real time, thereby to adjust timing of heat shut-off or kettle dump according to the progress of popping in the kettle.
Conventional popcorn poppers thus exhibit a number of problems, including:
The kettle and heating element are an integral package. This makes cleaning the kettle difficult since the heater cannot be immersed in water or placed in a dish washer. But if the nickel chromium heater is separated from the kettle, then heat transfer efficiency between the heater and the kettle structure is impeded.
The electrical cable connected to the heater is an integral part of the kettle/heater package and cannot be washed or placed in a dish washer.
Because the kettle necessarily moves each time the popped popcorn is dumped from the kettle at the end of each popping cycle, the electrical cable required to carry power to the heater necessarily moves, too, and thus is subject to flexural wear and corresponding breakage due to metal fatigue, resulting in maintenance and replacement expenses related to such electrical cable.
The heaters in conventional popcorn poppers are nickel-chromium heaters, which typically draw about 23 Amps at 240 VAC to produce approximately 5500 Watts of heating.
The challenge for the operator operating the popcorn popping machine is to leave the heater turned ON as long as possible in order to minimize the number of unpopped kernels, while turning the heat OFF soon enough that the popped popcorn product is not burned or otherwise degraded as a result of having been exposed to too much heat in the kettle.
The existing systems have no provision to use the actual end, or slow-down, of popping to detect the end of the popping cycle; but rather rely on either a timer, or operator discretion, to determine when to dump the popped popcorn contents from the kettle. But timers are objective devices, and are thus insensitive to variations in the time needed to pop different types of popcorn kernels, and are also insensitive to variations in heat output generated by different (e.g. first and second) heaters. Timers are also insensitive to differences in day-to-day operating conditions. So relying on timers is blind to the progress of the popping process in a particular cycle of popping of the popcorn.
Relying, instead, on operator intervention is subjective, and relies on operator skill, and good decision-making may be beyond the capabilities of sometimes-inexperienced operators. Accordingly, repeatedly making quality product is problematic for many operators of popcorn popping machines. As a result, the industry experiences significant quantities of burned and wasted popcorn, oil and salt, and/or low quality product with an excessive number of unpopped kernels, resulting in both reduced sales, and reduced profits for the owner.
In addition, there is a desire in certain instances to increase the rate at which popped popcorn can be produced, for high volume uses. Traditionally, the answer to high volume production needs has been (i) to employ additional popcorn popping machines or (ii) to increase the size of the kettle so as to pop a larger quantity of popcorn in each batch. Both answers come with their own set of problems.
Employing additional popcorn popping machines is accompanied by the requirement for additional staff to service the additional machines, accompanied by higher labor costs to the owner.
Increasing the size of the kettle avoids the requirement for additional staff, but typically provides inferior product, including increased number of unpopped kernels. In addition, larger kettles require more energy to pop the bigger batches of popcorn which, in turn, results in its own set of product quality issues typically related to burning the popcorn as a result of the need for relatively greater heat input to pop the greater quantity of popcorn kernels.
In order to achieve consistently reproducible popcorn popping, and to provide for increased production for high volume uses, it would be desirable to provide an improved operating control system as part of a popcorn popping machine including a cabinet for holding popped popcorn kernels, an electrically heated popcorn kettle located within the cabinet, a popcorn stirrer positioned within the kettle to stir the popcorn during heating, an air exhaust system for exhausting air from the cabinet, and an oil pump operably connected to a source of popping oil to supply oil to the popcorn kettle.
It would be desirable that such improved control system include electrical circuitry for connecting the kettle, the agitator, the exhaust system, and the oil pump to a source of electricity, and that such control system also include a micro-processor operably connected to the electrical circuitry to control operation of the kettle, the agitator, the exhaust system, and the oil pump during a cooking cycle.
It would further be desirable that such control system also include provision for detecting a condition or activity specific to a particular popping cycle, which informs either the operator or the micro-processor as to the degree of progress of the popping cycle, namely informing when heat to the kettle should be turned off in order to optimize the number of kernels left unpopped while avoiding burning of the popped popcorn product.